The invention relates to a system for traffic monitoring that aims at discouraging drivers to break the speed limits. The system identifies as speeding vehicles the vehicles that have had an average speed over the limit fixed for the monitored road. On the contrary, vehicles that have only temporarily passed the speed-limit, for example because of a quick and limited acceleration associated to an overtaking manoeuvre are not considered as speeding vehicles.
The system is therefore much more fare for the drivers, since it avoids the detested concept of speed-trap, and also for the authorities that with this system will be able to identify drivers that have kept a speed over the limit for at least a good fraction of the monitored road.
Other advantage of the system is that it is also much more secure for what concerns the traffic conditions. In fact, by checking the average speed of vehicles, it is possible to avoid typical sudden changes of the driving conduct, like for example abrupt breakings of drivers when they suddenly identify the location of a speed camera and also the consequent re-acceleration once passed the check-point.
With this system instead, the driver is forced to keep a prudent behaviour for the whole road distance monitored, which is ultimately the aim of speed-checking.
The system works automatically 24/hours a day and it guarantees the protection of privacy data since only the images relevant to speeding cars are sent to the central unit and the relevant authority officers.
The closest prior art to this invention is the average speed monitoring system disclosed in EP1276086. The system disclosed in EP1276086 is based on a statistical analysis of the characteristics of the vehicles in transit, and it is based on the low probability of vehicle mismatching, given the fact that the transit of vehicles usually happens in a limited amount of time between the two peripheral units.
The system proposed in EP1276086 goes beyond traditional vehicle identification systems, like the one in WO02082400 or WO2004/042673, mainly based on vehicle identification via an unequivocal identification of the plate of the vehicle. It is known and it is also explained in EP1276086 that an accurate identification of the car plate is very difficult for a number of reasons: change of illumination during the day and sometimes even between the remote locations A and B (see FIG. 2) because of sudden weather changes or because of different lighting conditions, or lack of reliable plate recognition system since plates, and characters, are different for the different countries.
For example German plates have the “o” that resembles a zero, the difference being a small cut on the zero; this small cut is though very difficult to be detected when there is a bit of noise on the images. Moreover German plates have two small circles between the part that identifies the city and the vehicle identification string. British plates have bigger numbers and different colours, as well as the Danish plates and so on. In order to identify correctly all these plates a specific algorithm should be used for each of the plate typology and this would be too onerous from the computational point of view.
The system and method of EP1276086 solves the failure of the previous systems by not unequivocally identifying the vehicles. It exploits some information relevant to the vehicle, such as dimension, colour, location of spots on the car and in this way it identifies the characteristics of the vehicle at the first and second remote unit, where the vehicles pictures are taken only with a rear view as in FIG. 2.a. 
In EP1276086 it is though not clearly explained how these vehicle characteristics are compared and used for the vehicle identification.
The method and system of the present invention overcomes the limitations of EP1276086 by exploiting a technology that in the following we will name as Plate Matching (PM). The technology of plate matching allows the establishing of correspondences between the plates detected by the peripheral units A and B without any limitation to the letter fonts used in a specific country.